Is My Design OK? Evaluating the Potential for Acoustic Vibration
Intense sound and vibration can be produced by gas flow through a heat exchanger array of tubes. Typically, the oscillating pressure corresponds to a transverse standing wave across the heat exchanger shell that is perpendicular to the crossflow and the tube axes. The sound is attributed to flow-induced pressure pulsations that are in sympathy with the transverse acoustic modes of the shell. As the velocity is increased, the sound can change mode. Acoustic resonance has occurred in inline tube arrays, staggered tube arrays, single tuberows; for finned and plain tubes; and in cylindrical and rectangular ducts. It has been observed with air, flue gas, steam, hydrocarbons, and two-phase gas-vapor flow. Sound pressure levels within a tube array can reach 176 dB and approximately 20 – 40 dB lower outside the shell. These levels can be physiologically disturbing and can also lead to structural damage. We will discuss methods for assessing the acoustic vibration potential of your shell-and-tube exchanger design.